brave-browser: Segmentation fault when launching a second window via terminal

Description

Segmentation fault when launching a second window via terminal.

Steps to Reproduce

1. Launch brave from terminal
2. Open a new terminal window and launch a second window
3. Console logs segmentation fault and exits but the second browser window is still opened

Actual result:

Release (Manjaro): No crash dump ID generated for release on Ubuntu

User namespaces are not detected as enabled on your system, brave will run with the sandbox disabled
Opening in existing browser session.
[106257:106257:0417/082009.710955:ERROR:sandbox_linux.cc(364)] InitializeSandbox() called with multiple threads in process gpu-process.
Segmentation fault (core dumped)

Beta: Crash Dump

brave-browser-beta 
--2019-04-17 08:46:19--  https://laptop-updates.brave.com/1/bc-crashes
Resolving laptop-updates.brave.com (laptop-updates.brave.com)... 151.101.21.7
Connecting to laptop-updates.brave.com (laptop-updates.brave.com)|151.101.21.7|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 16 [text/html]
Saving to: ‘/dev/fd/4’

     0K  
 Crash dump id:  5ad446cca388b589 
                                                  100% 2.18M=0s

2019-04-17 08:46:19 (2.18 MB/s) - ‘/dev/fd/4’ saved [16/16]

Segmentation fault (core dumped)

Dev: Crash dump

brave-browser-dev
--2019-04-17 08:47:01--  https://laptop-updates.brave.com/1/bc-crashes
Resolving laptop-updates.brave.com (laptop-updates.brave.com)... 151.101.21.7
Connecting to laptop-updates.brave.com (laptop-updates.brave.com)|151.101.21.7|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 16 [text/html]
Saving to: ‘/dev/fd/4’

     0K          
 Crash dump id:  16e3a3a988197e80 
                                          100% 2.06M=0s

2019-04-17 08:47:01 (2.06 MB/s) - ‘/dev/fd/4’ saved [16/16]

Segmentation fault (core dumped)

Expected result:

No segmentation fault to be shown when launching a second window via terminal

Reproduces how often:

Easy

Brave version (brave://version info)

Brave	0.62.51 Chromium: 73.0.3683.103 (Official Build) (64-bit)
Revision	e82a658d8159cabbd4938c1660f9bb00b4a82a23-refs/branch-heads/3683@{#902}
OS	Linux

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds? Yes

Website problems only:

• Does the issue resolve itself when disabling Brave Shields? N/A
• Is the issue reproducible on the latest version of Chrome? N/A

Additional Information

Issue originally reported on community. https://community.brave.com/t/second-launch-gives-segmentation-fault/53664/5

cc: @fmarier @bbondy